Other candidate genes for PTSD development include serotonin, dopamine and cannabinoid receptors (HRT2A, DRD3 and CNR1), dopamine transporter SLC6A3, monoamine transporter SLC18A2 (VMAT2), neuropeptide Y (NPY), C-reactive protein (CRP), retinoid-related orphan receptor (RORA), and the regulator of G-protein signalling (RGS2) [30,31,32,33,34,35]. Here, SLC6A3 is linked to post-traumatic stress disorder.